The present invention relates to a power loom. More particularly, it relates to a power loom for weaving of sieves or screens which has a fabric batton drive, a shaft (dobby) drive, and a shuttle drive.
Power looms of the above mentioned general type are used for producing fabrics of different widths and lengths. The productivity of these machines is determined substantially by the number of battons. It cannot be increased arbitrarily since for introducing of the weft thread between the warp threads a sufficient time must be available. It is required to correspondingly orient the warp and weft threads depending on predetermined application of the fabric. For woven paper machine sieves the dimensions are needed, which are longer in the direction of the weft thread than in the direction of the warp threads. This of course also influences the dimensions of the power looms which for such applications must have loom widths of 30 m. For introducing such long weft threads, a sufficient time must be available during a working cycle of the fabric batton. Correspondingly, the maximum possible batton number is limited. Moreover, the mass of the fabric batton must be moved. This mass grows proportionally with the fabric width and therefore additionally limits the possible batton number.
For increasing the productivity and avoiding the disadvantages connected with higher batton number, it has been proposed in the European patent document EP 0,321,274 to design a fabric batton drive for a power loom, which has a toggle lever moved by a complementary cam drive and articulately connected with a machine frame on the one hand and with the fabric batton support on the other hand. Due to the complementary cam drive the batton support performs a non-uniform swinging movement which provides more time for the weft thread introduction during a working cycle. The cam control of the fabric batton drive has however a disadvantage that when the number of battons is increased the rollers have the tendency for lifting from the cam disc and due to the mass moment of inertia disadvantageous reverse cycles are produced. Other known constructions involve providing a non-uniform movement of the fabric batton by the use of elliptic gear wheels or special crank drives.